Model S Winter Heating

[JoeyCoco]

This will be the first winter with a Model S - how mild a UK winter will be is anyone;s guess, though I have always been intrigued by the section in the manual:


"Using seat heaters to keep warm is more efficient than heating the cabin. To automatically limit the amount of power that the climate control system uses to maintain the temperature of the Battery and the cabin area, touch Controls > Driving > Range Mode > ON"

Aware that getting the heating a bit hotter than 20C you need to turn Range Mode off, though any guidance for those who have used the seat heaters... ??

Do they make a big impact, and in what type of time? Typically would have 3-4 seats unoccupied in the morning - so better to crank them all on?, or better to use a combination of both seat heaters & vents?

I also assume there are not other heating elements apart from rear window, as no side mirror heaters.

 

[arg]

Seat heaters work almost instantly, no need to turn them on in advance.

The main point is that you will have a very similar level of comfort with the seat heaters turned on and the main heater turned down a couple of degrees, compared to using the main heater those couple of degrees warmer - but will use vastly less power (IIRC, the main heater is about 7kW at full blast, the seat heaters a couple of hundred watts).

The effect of the 'range mode' setting is less obvious; it aims to change the control of the main heater to use less energy at a given temperature setting, presumably by less overall airflow (when in auto mode), also I believe by taking longer to hit the target temperature.
I don't find it to make a great difference, though my car is a RWD where the 'range mode' only affects the HVAC; if you have a 'D' car, the range mode also affects the power split between front/rear motors and is more likely to have a significant effect on a long trip.

Side mirror heaters are linked to the control for the heated rear window.

I assume you have already found the double-tap on the 'demist' button to give max hot air to the screen for urgent (energy no object!) clearing.

The other piece of winter advice is that, for range planning of long trips (which is the only sort of trip where you care), the extra energy consumption mainly comes as a large 'departure tax' to get the car up to temperature. So a long continuous trip is not so much worse in winter than in summer, but one where you stop several times along the way for a few hours (or worst of all an overnight without charging) has a significant penalty.

 

[spottyq]

I think you are overthinking it.

During normal driving, just use the normal climate control, and set the heating seat to whatever you feel confortable.

For long trips, pre-heat before you start (this is the most important part) then set range mode on.

If you know you will be cutting it close, set the climate to be a few degrees colder and crank the heated seats up.

(Turning on the seat heaters of an unoccupied seat will have a negligible, and probably negative effect on energy efficiency overall. It does not makes sense.)

[Edit:] @arg beat me to it.

 

[DJP31]

I think it depends on just how energy efficient you want to be. My car is plugged in most evenings so I will use the app to turn the heating on 10 or 15 minutes before leaving time, and the car will use the power source and not the battery. That way I’m not using up range.

The rear window demister isn’t brilliant, I guess California doesn’t have even UK winters, but the side mirrors are heated too. I have the sub zero pack, it does get chilly in Surrey afer all, and the heated steering wheel is excellent.

I certainly wouldn’t turn all the seats on, maybe the manual is assuming passengers are on board.

I’ve also never used range mode, I’m never in trouble range wise and am not interested in limiting the power or reducing any of the cars functionality in name of saving a few kW’s here and there. YMMV

 

[WannabeOwner]

Never been able to get our feet warm in Winter ... other than that I use the Phone APP to turn climate on some minutes before departure - Winter or Summer - both to have the benefit of a pleasant car temperature when I get in, and, if car is plugged in, to use Shore-power rather than battery.

I use Range Mode on longer journeys - my understanding is that it only makes a worthwhile difference to power saving on Dual Motor models [or is it P-models?] - by using the smaller motor alone in preference to large motor- but Range Mode also reduces cabin heat. A mode that conserved power to motors, but still kept the cabin warm, would suit me better.

 

[kort677]

even in the most extreme cold temps I've encountered being in Colorado during the winter I found that other than warming the cabin to bring the temps inside to a reasonable level the seat heaters will keep you comfortable. using the heating in the tesla in cold conditions will have an extreme impact on range and should be avoided if possible.

 

[arcus]

Seat heaters are favored over cabin heating. The manual also suggests that (page 62 and 97).

 

[cyberkryten]

I no longer bother with range mode. I do the same journeys over and over again and traffic, weather conditions and outside temperature make far more difference than whether range mode is on or off.

My standard trip to London and back, leaving the car parked for 4-6 hours can end up with me arriving home having used anywhere between 80% to 95% of the (P85D L) battery, regardless of range mode setting.

I tried initially to determine how much power it saves, but I was totally unable to tell from the journey data whether it was on or off for a given journey, so I no longer bother using it at all.

 

[Brass Guy]

Seat heaters use MUCH less energy than the cabin heater. The cabin heater uses significant energy and can reduce range dramatically. Seat heaters use a negligible amount of energy, not even enough to show as a single pixel on the energy meter.
Seat heaters will not heat the cabin, that's not what they're designed to do. Leave unoccupied seats' heaters off, it'd just be a waste.

Aside from reducing the cabin heater, Range Mode also limits (or disables - I'm not sure) the battery heater.
In the winter time if you have rather short drives, spread out through the day, the battery heater is a waste. For example I may leave for a total of 15 minutes during the work day to pick up lunch and return. Having been at work for half a day, the battery is cold (regeneration is restricted or disabled). It will try to heat the battery, and regeneration begins to return just about the time I get back to work. This will pretty much double the energy use for the trip. Then the car will sit in the cold for another half day and when I leave for my 15 minute trip home the same thing will happen.

My current mode of operation is I will use range mode in the winter to prevent unnecessary battery heating, and range mode off in the spring to ensure the battery is cooled properly for maximum longevity.

Alternatively, you could just leave range mode off, stop thinking about energy use, and enjoy the car. (I cannot just do that though.)

 

[12Pack]

My current mode of operation is I will use range mode in the winter to prevent unnecessary battery heating,

But I understand leaving range mode ON during charging makes it less efficient, as it takes longer for the battery to come up to charging temp ..

 

[jerry33]

But I understand leaving range mode ON during charging makes it less efficient, as it takes longer for the battery to come up to charging temp ..

When plugged in range mode should be off to allow battery heating. Turn the heat on from the App 20-30 minutes before driving. When driving range mode should be on. Range mode has the greatest effect on short trips. It's less effective on long trips, and in summer it makes almost no difference regardless of trip length. The criteria I use is that 17C or less use range mode when driving, otherwise don't bother.

 

[Brass Guy]

I wasn't going to get that deep into it, but yes, in the winter I try to remember to turn off range mode when I get home and back on when I leave. I also time the charge to finish (or almost; since I don't need it to finish) shortly before I leave in the mornings.

 

[barjohn]

In colder weather do you turn the AC to off or leave it on? Does it make any difference?

 

[Tam]

In colder weather do you turn the AC to off or leave it on? Does it make any difference?

I set everything "Auto" so I don't have to turn A/C or Heater on or off and it would adjust to my temperature settings in cold winter and hot summer too!

 

[Terry_B58]

In colder weather do you turn the AC to off or leave it on? Does it make any difference?

The AC is a must to aid the demist of the screen. So leave it on Auto.

 

[Brass Guy]

I turn off the AC compressor, also manually set recirculate so it doesn't have to heat frigid air. This works if it's below freezing without precipitation. I don't know how much difference it makes.
If it's above freezing and rainy, it will fog up so I alter settings. I first return intake to Auto; that's usually enough if I'm the only one in the car.

 

[arg]

If it's above freezing and rainy, it will fog up so I alter settings. I first return intake to Auto; that's usually enough if I'm the only one in the car.

Question is, does increasing the proportion of outside air (dry but cold, so needs heating) use more or less power than continuing to recirculate but using the A/C to dry it?

The answer to that question probably varies with conditions, so the question then becomes whether you or the car's software (auto mode) are better at making that call. I'm willing to believe either possibility.

 

[Brass Guy]

My thought was that the AC is not only using energy, but also still cooling the air. It could be more efficient to use the AC and recirculate though, I doubt the AC is cooling the air to below freezing. I should reconsider my settings depending on the outside temperature.

As near as I can tell, the auto settings always incorporate AC and fresh air. I've found these are not necessary to keep a clear windshield when its cold and dry. I figure you must preheat the car, else your breath will freeze on the glass.

 

[DJP31]

I try not to over think things. With every car I’ve had that has climate rather than AC I set it to auto, set the temp and off I go. Direct max to the windscreen on occasion to clear, on the Tesla a simple “double tap”, and that’s it. Never had any problems in any of the cars I’ve had.

 

[Ianf]

Full auto, and use the app to pre-defrost for 10 mins in the morning is pretty good. Sometimes need to use the double tap to get the air warm enough if it's cold and damp once you get in, for a couple of minutes. Once driving full auto and 21 is comfortable enough + level 1 seat heating. If you are having trouble de-misting, check the lower trunk is not damp.